CVE-2026-84695
Description
BookStack before 26.05.4 contains a stored cross-site scripting vulnerability in the drawing upload endpoint that accepts unvalidated base64 content and stores it without content inspection. Attackers with editor permissions can upload SVG files containing scripts that execute in administrator browsers when accessed through the image gallery API without content-type validation or CSP headers.
Predictions
Heuristic predictions, AS-IS, for prioritization only.
Mitigations
No mitigations published for this CVE yet.
The vendor-content worker queues fetches as references arrive (check back in a few minutes). Or — if you've already worked around this in production — publish your fix to the community-verified tier.
Propose a mitigation on Community Mitigations published via the community go through AI scoring + 2 human reviewers + 7-day silent objection window before landing here withsource_tier=community-verified.
References
- https://github.com/BookStackApp/BookStack
- https://github.com/BookStackApp/BookStack/blob/v26.05.3/app/Uploads/ImageService.php
- https://github.com/BookStackApp/BookStack/commit/ac0348a79f3ddd004ca87703948cb9c7d19a420a
- https://github.com/BookStackApp/BookStack/releases/tag/v26.05.4
- https://www.bookstackapp.com/blog/bookstack-release-v26-05-4/
- https://www.vulncheck.com/advisories/bookstack-before-26.05.4-stored-xss-via-drawing-upload
CWEs
CWE-79
Community-verified mitigations for this CVE will appear above when contributors publish them.
Verify integrity in audit chain (admin only). AS-IS.